1. Field of the Invention
The present invention relates to a film-forming composition, an anti-reflection film using the film-forming composition, a polarizing plate and an image display apparatus (particularly a liquid crystal display) using the anti-reflection film.
The present invention also relates to a coating composition for an anti-pollution article excellent in an anti-pollution function by water repellency and oil repellency, and an anti-pollution article having a cured film of the coating composition. In particular, the present invention relates to a coating composition for an anti-pollution article capable of forming anti-pollution layers on the surfaces of optical members (e.g., an anti-reflection film, a polarizing plate, an optical filter, an optical lens, a liquid crystal display, a CRT display, a projection television, a plasma display, an EL display and the like) without impairing the optical performances of various optical members, and relates to an anti-pollution article having a cured film comprising the coating composition.
2. Description of the Related Art
An anti-reflection film is generally arranged on the surface of an optical product to reduce reflectance by using the principle of optical interference for the purpose of preventing the reduction of contrast and mirroring of images by the reflection of outer light, in particular, in image display apparatuses such as cathode-ray tube (CRT), plasma display panel (PDP) and liquid crystal display (LCD) which are required to have good visibility, the film is arranged on the outermost surface of the display.
These anti-reflection films are generally manufactured in many cases by forming a low refractive index layer having an appropriate thickness on a high refractive index layer. As the materials for a low refractive index layer, materials having the lowest possible refractive index are desired from the viewpoint of the property of anti-reflection, and at the same time, high scratch resistance and an anti-pollution property are required, since it is used on the outermost surface of an image display apparatus. For reducing reflectance, the uniformity of film thickness is important, and a coating property and a leveling property are also important factors in coating type materials.
On the other hand, base materials such as metals, glass and resins are conventionally widely used as the parts of motor vehicles, office automation equipments and household electrical appliances and the like, but the surfaces of these base materials are polluted by the adhesion of floating dusts in cars, offices and rooms, by the adhesion of oily substances contained in foods and machine oils difficult to be wiped out, and the adhesion of fingerprints during use. Accordingly, various means are adopted to make dirt difficultly adhere to the surfaces of base materials and contrivances concerning scratch resistance and an anti-pollution property are taken so as to easily remove once adhered dirt without scratching the surfaces.
Particularly in optical members, such as anti-reflection films, polarizing plates, optical filters, optical lenses and image display apparatuses, fingerprints, sebaceous matters, sweat and cosmetics are often adhered by the use. Such dirt once adhered cannot be removed easily and in particular optical members with anti-reflection films show adhered dirt, which is a problem.
As means to improve an anti-pollution property and scratch resistance while maintaining low refractive index, it is effective to impart a sliding property to the surfaces of optical members, e.g., the addition of fluorine compounds and silicone compounds. These means lower surface tension and are also expected to be effective to give a leveling property. As fluorine-containing polymers that are low refractive index compounds, fluorine-containing olefin copolymers reveal extremely high water repellency, oil repellency and show good anti-pollution property by —CF2— groups or —CF3 groups orientated on the surfaces of films, but they are hardly soluble in solvents, so that it is difficult to obtain membranes by coating.
In regard to this subject, methods of improving a coating property by introducing polysiloxane components are disclosed, such as a fluorine-containing olefin copolymer introduced thereto a polysiloxane block copolymer component by a silicone macro-azo initiator (JP-A-2000-313709), a polymer reaction of a fluorine-containing olefin copolymer containing an epoxy group with polysiloxane containing an amino group (JP-A-56-28219), and a polymer reaction of a perfluoroolefin copolymer containing a hydroxyl group with polysiloxane containing an epoxy group (WO 98/29505).
Film uniformity is greatly improved by these methods but the orientation of the main chain of perfluoroolefin polymer on the outermost surface of the film after being cured becomes insufficient, as a result an anti-pollution property lowers or the film is deteriorated by the use for a long period of time.
Further, low refractive index layers comprising a cured polymer film having an alicyclic structure containing fluorine-containing hetero atoms which are well soluble in specific fluorine solvents are disclosed (JP-A-8-122502, JP-A-11-209685 and JP-A-8-234002) but these layers cannot satisfy required abrasion resistance. Cured film using a copolymer having a perfluoro alicyclic structure not containing hetero atoms are also supposed (JP-A-2001-200019 and JP-A-2001-272504).